Axial pipe-soil interaction during pipeline-walking analysis of pipelines placed on Bohai sand

Abstract

Pipeline walking induced by heat-up and cool-down cyclic loadings during shutdown and restart cycles is a challenge in the design of relatively short pipelines exposed on seabeds. A major source of uncertainty in the analysis of pipeline walking is the pipe-soil response, which has a significant influence on pipeline walking. To investigate the pipe-soil response during pipeline walking, a set of large-scale model tests are conducted on Bohai sand, and they involve axially moving pipelines with different speeds and cycles. Based on these test results, bi-linear pipe-soil interaction models with normalization of the pipe weight and diameter are proposed for Bohai Bay sand. Subsequently, a comparison of the model test data to existing pipe-soil interaction models is performed, and the existing pipe-soil interaction models are calibrated with site-specific soil properties of Bohai Bay sand. Finally, the application of the site-specific pipe-soil interaction models for a pipeline-walking analysis of pipeline placed on Bohai Bay sand is performed with the finite element method to study how pipeline walking is influenced by these pipe-soil interaction models. Combined with the influence mechanisms, a design model is proposed that considers the potential risks of pipeline walking in pipeline design to reduce costs without compromising reliability.